There is a market demand for transmission equipment (e.g., high definition video interface (HDMI) equipment) that converts an input between different voltage levels and that both consumes less power and has higher-bandwidth than conventional transmission equipment. An example of the transmission equipment is equipment that is high definition video interface (HDMI)-compatible. HDMI is a specification that integrates audio and video information into a single digital interface to be used with, for example, a digital video disc (DVD) player, a digital television (DTV), a high definition TV (HDTV), a set-top box, and other audio and/or video devices. The high definition multimedia interface supports standardized, enhanced, or high-definition video formats along with multi-channel surround sound audio. Some of the benefits of high definition multimedia interface may include, but are not limited to, uncompressed digital video, and a single connector instead of multiple connectors and cables.
In conventional devices, serializer outputs are high-speed, rail-to-rail signals in a 1.0V power domain. In order to drive over 10 mA of current, a driver after the serializer is conventionally a large n-type metal-oxide-silicon (NMOS) differential transistor pair. The input capacitance of the NMOS differential pair is high, which limits a bandwidth of the conventional device.
Further, since the conventional driver uses an open drain structure, a majority of the driver's current comes from a power supply having a voltage that is higher than 1.0V (e.g., 3.3V). Thus, there is a demand for a high speed, high performance circuit to convert the input from the 1.0V power domain into a power domain that is intermediate between the 1.0V power domain and the higher power domain.
Accordingly, there are long-felt industry needs for methods and apparatus that mitigate problems of conventional methods and apparatus, including a high-speed pre-driver and voltage level converter with built-in de-emphasis for HDMI transmit applications.